(Hi there Old Timer I have a couple of other thoughts on why the quality of the vars has slipped in Holland I think the main one is the way they grow or should I say the type of lighting they use. Most of the strains they have came from America and were either developed under real sun or under big halides and both these sources have a big uv content. The Dutch are great gardeners and have had to use supplementary lighting in their glass houses for years so they can grow all the year round. The lights they developed were a highbay type such as Poots and Phillips fixed on grids 5 ft or so above the finished plant canopy . And of course they chose the lamp that gave the most photoactive lumens per w, the sodium lamp which has virtually no uv output. Of course when cannabis came to Holland the farmers son who decided grow a bit of pot used the same system as in dads 2.5 acre glass house. There is no doubt that all the most potent varieties of cannabis come from areas of the world where the background uv is high to extreme and that the potency and complexity of high relates the almost directly these uv levels. Cannabis is a highly adaptable and over a few generations change to new conditions and this is what I think has been happening in Holland. I could go into more detail but this is not the board to do this on but it does relate to your comments. It is interesting to notice that Greenhouse seeds have mentioned uv for the first time I think this must have come from Nevils input and if they are now taking this into account maybe things are turning to the better. As far the var you were asking about I suspect D J Short would be the man to ask, from I can glean he is a very private person. You could try writing to him care of Mark Emery sorry I cant help futher. All the best have a great Crimbo all. Ot1.
O. K., but does U.V. content change genetics? Read in a Tom Flowers book on forced mj flowering, that MJ grown on higher elevations, ie, 10,000 ft. tested for higher THC content. I assume this is the plant's response to this particular environment. I have always rotated my plants between sun vice HPS, security and weather conditions permitting, and can't complain re potency and growth habits. So.....are you proposing that genetics have been altered on a short term, or a long term basis, regarding particular light setups by the Dutch? Uncle Ben
I think it is a problem that has been developing through the generations. Wernard of [Positronics] was aware of it being a problem and now Greenhouse seem to be taking it on board. I haven't read Tom Flowers but high elevation plants that have been there for generations are high in thc but more importantly it is a lot more complex. On a short term basis a clone from a known variety Indica type will have a slightly more up high with the addition of uv during flowering but Sativas seem to improve a lot more with a much clearer up high. I would suggest that if breeding for seed indoors the addition of uv a/b tubes as supplementary lighting would help to improve the stock a lot . Your plants getting some real sun would probably allow them to express the potential of that generation. You can easily test this If you make a number of cuttings from a mum and grow half with sodium only and supplement the other half with sun when you can, I think you will find quite a difference between the two stones the more sat in the var the bigger the difference. Ot1.
After a quick 'Altavista' search on UV and cannabis I came up with a few items that pertain to this discussion. Here is the first: Pate, D.W., 1994. Chemical ecology of Cannabis. Journal of the International Hemp Association 2: 29, 32-37. The production of cannabinoids and their associated terpenes in Cannabis is subject to environmental influences as well as hereditary determinants. Their biosynthesis occurs in specialized glands populating the surface of all aerial structures of the plant. These compounds apparently serve as defensive agents in a variety of antidessication, antimicrobial, antifeedant and UV-B pigmentation roles. In addition, the more intense ambient UV-B of the tropics, in combination with the UV-B lability of cannabidiol, may have influenced the evolution of an alternative biogenetic route from cannabigerol to tetrahydrocannabinol in some varieties.
How about this one: Another stress to which plants are subject results from their daily exposure to sunlight. While necessary to sustain photosynthesis, natural light contains biologically destructive ultraviolet radiation. This selective pressure has apparently affected the evolution of certain defenses, among them, a chemical screening functionally analogous to the pigmentation of human skin. A preliminary investigation (Pate 1983) indicated that, in areas of high ultraviolet radiation exposure, the UV-B (280-315 nm) absorption properties of THC may have conferred an evolutionary advantage to Cannabis capable of greater production of this compound from biogenetic precursor CBD. The extent to which this production is also influenced by environmental UV-B induced stress has been experimentally determined by Lydon et al. (1987). Their experiments demonstrate that under conditions of high UV-B exposure, drug-type Cannabis produces significantly greater quantities of THC. They have also demonstrated the chemical lability of CBD upon exposure to UV-B (Lydon and Teramura 1987), in contrast to the stability of THC and CBC. However, studies by Brenneisen (1984) have shown only a minor difference in UV-B absorption between THC and CBD, and the absorptive properties of CBC proved considerably greater than either. Perhaps the relationship between the cannabinoids and UV-B is not so direct as first supposed. Two other explanations must now be considered. Even if CBD absorbs on par with THC, in areas of high ambient UV-B, the former compound may be more rapidly degraded. This could lower the availability of CBD present or render it the less energetically efficient compound to produce by the plant. Alternatively, the greater UV-B absorbency of CBC compared to THC and the relative stability of CBC compared to CBD might nominate this compound as the protective screening substance. The presence of large amounts of THC would then have to be explained as merely an accumulated storage compound at the end of the enzyme-mediated cannabinoid pathway. However, further work is required to resolve the fact that Lydon's (1985) experiments did not show a commensurate increase in CBC production with increased UV-B exposure.
"The MV (mercury vapor) lamp produces more UV-A, violet and blue light than any other type of lighting source commercially available. Cannabis responds to the intense violets and blues of the murcury vapor lamp by producing dark, almost bluish green leaves. Stalks grow strong but not straight and sort of zigzag between short internodal lengths. Side-shoot development is extensive, as is the formation ofresin glands on calyxes, bracts and larger associated leaves. Poetency is very noticeably increased when compared to clones grown under other hid lamps. Plants also rejuvenate faster under mv lamps." Just part of an excellent article by Owl(one of my fave growers). Peace
7. IMPACT OF UV-B ON PLANTS AND ANIMALS UV-radiation has long been known to be damaging to life; indeed this quality is being employed increasingly for the disinfection of water and for the mutation of microorganisms for laboratory experiments . UV-B affects plants and animals by modifying both their biological and chemical environment. Damage may occur in a number of ways, including the direct destruction of the genetic material DNA, deactivation of enzymes, disruption of membranes and other cell structures and the generation of highly reactive chemical agents known as "free radicals". Although biological repair mechanisms exist, mutations may remain as errors in the repair processes. In addition, the repair mechanisms themselves may be deactivated by high UV doses. The interaction of all these processes can lead to a variety of adverse effects on plants and animals. Many effects are sub-lethal, may interact with other factors and may, therefore, be very difficult to attribute to UV-enhancement specifically. Effects on plants in the sea, in freshwater and on land are of fundamental importance because of their position at the base of all other food chains. By nature, plants have evolved to maximize the surface area they expose to sunlight, but consequently their exposure to damaging UV-radiation is also increased. Elevated UV exposure can cause temporary or irreversible damage to photosynthetic apparatus (including the bleaching of the pigments which trap the sun's energy), to processes of cell division and growth regulation, and to the composition and replication of genetic material. Consequences include a reduction in growth yield, changes in levels and effects of plant hormones and alteration of periods of dormancy, flowering, etc. UV-B IMPACTS ON TERRESTRIAL ECOSYSTEMS Increases in UV-B radiation:
Alter soil quality and the soil ecosystem; Decompose soil litter; Influence plant growth; Influence plant life cycles including timing of flowering, leaf-drop, dormancy and death; Alter biogeochemical cycling of carbon, nitrogen, etc.; Affect susceptibility of plants to disease, drought, temperature and pollution; Modify the distribution of species within an ecosystem; Disrupt the terrestrial food chain; Alter inter-species competition for food, light and space; Damage eggs and larvae of terrestrial fauna.
tom flowers has a bit to say re uv from his flower forcing book: Marijuana is thought to be indigenous to foothill areas with elevations of 1500-2500 feet [where there's high uv levels]. Many experienced growers will tell you pot grown at these elevations will be the most potent - up to 20% more potent than the same variety grown at sea level. Growers use two or more 20 minute UV light treatments during the day cycle. Most [tanning] UV lights have timing units. [small face-tanning lights for 400w, full body tanning systems for 1000w areas. used tanning lights supposedly available cheap] If you have to be in the growing area wear sunglasses that filter out UV light and a hat. The small amount of UV-b radiation these lights produce can do heady things to your marijuana. Don't get carried away though, the object is not to get the plants to glow in the dark.
All these new strains are made with kick ass lightning, there are no seeds breedders that are using fluo lightning so the plant after regenerating with so much light all his life tend to include this trend in his genetic pattern. They don't breed seeds for low light level YET> There are some older strain like NL that work well under low lightning. POTENCY> Metal halide coated cooler than sunmaster warm but the blue spectrum does some tricks with potency. let's say we talk about ordinary Northen light strain. I did always found a high level of CBD and CBN in NL when grown under to much red CRI. I think that since the resin is there to keep the flower from drying (natural no) it must make sens to keep the leaves alive and feeling well for a longer period so that the leaves can produce that thick enveloppe you need to keep those resin glands from oxidysing ( ouf) The blue spectrum will work on the resin glands to produce THC . Forrest of dreams.......
Metal halide produce the best potent weed less lumens for the money but better smoke. After years of testing with some friends who did want to keep THEIR recipe (more hps) i foung there weed to be harsh, full of CBD, make me eat and sleep, only good to sell to someone else taht you dislike. The blue spectrum will give you a final product that have everything included :taste without curing, potency and yield, To be effective a ratio of 2 MH for 1 hps at the most.(hps) Hps alone can produce a cash crop but not a connaisseur crop. Et Voila...
Ahhh ok.of Cannabis grown in Afghanistan at 1,300 meters (4,350 feet) elevation show that significantly more propyl cannabinoids are formed than the respective pentyl homo-logs. Other strains from this area of Asia have also exhibited the presence of propyl cannabinoids, but it cannot be discounted that altitude might influence which path of cannabinoid biosynthesis is favored. Aridity favors resin production and total cannabinoid production; however, it is unknown whether arid conditions promote THC production specifically. It is suspected that increased ultraviolet radiation might affect cannabinoid production directly. Ultra-violet light participates in the biosynthesis of THC acids from CBD acids, the conversion of CBC acids to CCY acids, and the conversion of CBD acids to CBS acids. However, it is unknown whether increased ultraviolet light might shift cannabinoid synthesis from pentyl to propyl pathways or influence the production of THC acid or CBC acid instead of CBD acid. The ratio of THC to CBD has been used in chemotype determination by Small and others. The genetically determined inability of certain strains to convert CBD acid to THC acid makes them a member of a fiber chemotype, but if a strain has the genetically determined ability to convert CBD acid to THC acid then it is considered a drug strain. It is also interesting to note that Turner and Hadley (1973) discovered an African strain with a very high THC level and no CBD although there are fair amounts of CBC acid present in the strain. Turner* states that he has seen several strains totally devoid of CBD, but he has never seen a strain totally devoid of THC. Also, many early authors confused CBC with CBD in analyzed samples because of the proximity of their peaks on gas liquid chromatograph (GLC) results. If the biosynthetic pathway needs alteration to include an enzymatically controlled system involving the direct conversion of hydroxy-CBG acid to THC acid through allylic rearrangement of hydroxy-CBG acid and cyclization of the rearranged intermediate to THC acid, as Turner and Hadley (1973) suggest, then CBD acid would be bypassed in the cycle and its absence explained. Another possibility is that, since CBC acid is formed from the same symmetric intermediate that is allylically rearranged before forming CBD acid, CBC acid may be the accumulated intermediate, the reaction may be reversed, and through the symmetric intermediate and the usual allylic rearrangement CBD acid would be formed but directly converted to THC acid by a similar enzyme system to that which reversed the formation of CBC acid. If this happened fast enough no CBD acid would be detected. It is more likely, however, that CBDA in drug strains is converted directly to THCA as soon as it is formed and no CBD builds up. Also Turner, Hemphill, and Mahlberg (197
